Hearth & Home Technologies CUMBGAP-MBK Manuale Utente

R

Page 8

September 1, 2008

7006-188E 

The k value indicates the amount of heat (in BTU’s) that will flow 
in 1 hour through 1 square foot of a uniform material 1 inch thick 
for each degree (F) of temperature difference from one side of 
the material to the other.  The LOWER the k factor means less 
heat is being conducted through the non-combustible material to 
the combustible material beneath it.  The k value of a material 
must be equal or smaller then the required k value to be accept-
able.
  (BTU) 

(inch)

  (foot

2

 (hour) (

o

F)

The R value is a measure of a material’s resisteance to heat 
transfer.  R value is convenient when more than one material is 
used since you can add the R values together, whereas you can 
not do this for k value.  The HIGHER the R factor means less 
heat is being conducted through the non-combustible material to 
the combustible material beneath it.  The R value of a material 
must be equal or larger then the required R value to be accept-
able.

Divide 1 by k and multiply the results times the thickness in inch-
es of the material.

 

R = 1/k x inches of thickness

Divide the inches of thickness by R.

 

k = inches of thickness/R

Example: Floor protection requires k value of 0.84 and 3/4 inch 
thick.

Alternative material has a k value of 0.6 and is 3/4 inch thick.

Divide 0.6 by .75 = k value of 0.80.  This k value is smaller than 
0.84 and therefore is acceptable.

30-3/8"

52"

required coverage

16"

38-5/8”

optional

coverage

34-5/8"

8"

Front fuel 

loading door

52"

optional coverage

optional

coverage

8"

optional

coverage

44-3/4"

optional coverage 

optional

coverage

18-5/8"

48-7/16"

53-7/16"

16"

16"

required coverage 

25-3/4"

11-1/8" 

8"

38-5/8"

Fuel loading 

door

Floor protection must extend 
length of flue and 2" (51mm) 
beyond each side of pipe 
(shaded area)